Elastic wave television system



P 1934- A. MCL. NICOLSON 2 ELASTIC WAVE TELEVISION SYSTEM Filed July 1, 1932 IElEr. l- Elfin-7 E laud-E 72 /'75 INVENTORS ATTORNEYK 25 P Alexander MELEHII Nipulsun Patented Sept. 4, .1934

' .9. 2 ELASTIO- WAYQ TELEVISION SYSTEM Alexander McLean NicolsomNew York, N. 31., s-

signor to Communication Patents, Inc., New Form Y'., a corporation of Delaware Application July "1,; 1932,"Serial No. 620,380 '15 Claims. (01;. 178 6) This invention relates to electrical transmis sion systems, and particularly to such systems adaptable for. the initiation and reception of electrical impulses characterized bythe .light and 5 Shade densities of objects 'or images thereof.

' An object of the'invention is to initiate electrical impulses characterized by the light and shade densities of objects and transform such impulses into varying light intensities proportional IQ theretot Another objectof the invention is to obtain greater efliciency of reproduction of light images and to retain any desired image indefinitely. A further object of the invention is to produce,

18. with a given amount of light, images having a brilliancy many times greater than that obtainableatpresent j Y A still further object of the invention is to produce a commutating efiectwithout the .use of any I '20 mechanical moving parts except thatof wave motion within a metallic medium.

Tlrepresent type of television transmission and reproduction of images has been "basedpn the r principle of scanning or exploringr 'l'hisjprin- 25. ciple in brief, is the obtaining of electrical cur:

rents proportional to the light, and shade densities of unit areas of objects in a serialordereachunit area of the object or. image providin fa certain current amplitude or frequency whichrepresents "30 the light intensity value upon thatnnit area.

It is necessary with such asystem to produce all theunit areas within a time interval whichpermits the eye to retain the first light impulse dur ing theentire period of scanning. Furthermore,

to obtain the illusion of motion of objects,'it is necessary to present each full image at. the rate of at least ten images. per second: i .Basing further conclusions on the. present standard speed of transmission which is sixty '46 lines at twenty repetitions per second, eachun'it area is, therefore, presented to the. eye during '1/72,000 of a second. With sixty lines there ex ists approximately 3 600 unit areas each' of which is scanned and presented to' the eye at this'rate.

5 It is obvious, therefore, that .an intense light .55 disclosure together with a commutator operating without mechanical moving parts except the movement of certain mediums caused by the transmission of waves therethrough. It is Well known mechanically that the speed of transverse waves along elastic mediums such as a wire. is determinable by the tension in the wireand the nature of the material making up the wire. These waves may bepropagated at a rate exceeding 2000 feet per second. In the same type of medium a longitudinal wave may be propagated at even greater speeds. In the present disclosure one or both modes of vibration are utilized, some modifications employing the heterodyne principle 'well 'lrnown in the electrical art in which. two elastic frequencies produce. a beat note to which l0v a mechanical element is resonant. This elastic wave commutating system is being claimed in a divisional application Serial vN0. 687,950, filed September 2, 1933.

'To obtain the persistency eiTect, that is, the retention of .the light on a unit area for a period of approximately l/20th of a second, a plurality, of shutters tor gates representing'each unit area is adjusted by the incoming current impulses to pass aduantity of light proportionalto the'strength of the incoming impulse. 'This gate or shutter adjustment is"maintained during the time period required to adjust the other shutters and continues 'in'its original' adjustment until such instant as the light intensity changes for that unit area. A system is thus disclosed in which only the shutters representing. unit areas varying in intensity are operated thereby providing, in effect a constant image. An oscillatorof the periodic type provides the timing impulses for the shutters which when disconnected permits the maintaining of any imiage present at the instantof disconnection.

' The invention may be more fully. understood by reference to the following detailed description read in -conjunction with the accompanying draw?- ingin which: I j

'I,Fig. 1 is a diagrammatic view of a receiver.

j, Fig.2 is an elevational view of the persistent screen employed in the system.

Figs/3, .4, 5, and 6 are detailed views of the 100 shutteremployed in the screen of Fig. 2. p

Figs 'l and 8 are views of a heterodyne type'of shutterscreen: and, Figs.'9 and 10 are modifications of elastic wavetransmitters for operating the screen of Fig. 2.

'Referring specifically to Fig. 1 which is il1us-' trating a'receiving system, an antenna 5 or wire terminal 6 may impress on a receiver 7 incoming currents characterized by the light and shade densities of unit areas scanned at a distant point. 110

The image may be scanned in any well known manner such as by the spiral aperture disk method, cathode ray or are scanner, the latter being shown in my U. S. Patent No. 1,863,278, of June 14, 1932.

The output of the receiver 7 is impressed upon a solenoidal type of field represented by a single turn 8, this solenoid surrounding a gate ;or shutter type screen 10. The screen is actuated by an oscillator 11. A source 13 energized from a supply 14 provides constant intensity light which is projected upon the screen 10 through a lens 15 and so focussed by the aid of multiple lens 11 7 as to be properly projected upon a screen 16 to any desired size, the lens 1'7 eliminating the flladow of the shutter supports. A lattice frame 18 covers the spaces between shutters.

Referring now to Fig. 2 in which the screen-'10 is shown in more detail, a frame is composed of two massive sections 20 and 21 with smaller sections 2.2 and 2.3,- There is strun between the sections ,23 and 2.1. a p rality of wires 25 of a gauge in acco d n e wi h he size of the screen u dv'lhese wires are adjustably attached to the sections ,23 and pass throu h section 21 to ti hteni 26. The section 21 is of a composite type in that it is composed of layers of wave absorbing material, that s, th first layer may be of cork, he sec nd of fibre, and the third of harder substance, such as rubber or bakelite and so on to th k s tion which may e of steel to obtain the n cessary supp rt for .tensionihg h wire .Polqpehdicular to, and adjacent Wires 25, and sey el auges lar er. is a drive wire 28 i connected to the wires25 through vertical project tions 9. The wire 28 may be atta hed to an a sorlo ngse'ction similar tosection 21. The p i o tion 29 are a par of the wires 25, tha the wir s 25 may be looped at points 30 and connhfll od to the frame section 23 by shorter sections 31, while the upper points. oi the projections are attached to the wire 28. It is obvious fr m 'oohstruo ti h that a transverse wave in the wire .28 he plane of the scr en will produce ,a simila wa e in the wire 2.5 in the plane .ofthe screen bot-with its d rect n o motion shifted 9.0 Mounted upon the Wires 25 are a plurality of m tallic gate or hutter sectionsfit whichwill he described and shown in more detail lot-er. The Wire 2: is acti v d by means of a elay .3& supp i d from the oscillator ll of a type which prelerahly p d ces a p aked wav form of only ahalf cy le at definite intervals. Th fi ld windin .8 i shown in the term of a. sin le coil and completely surrounds screen 19 to produce therein a uniform magnetic field The receiver 7, antenna 5, and wire t rniinal 6 are shown s in F l.

n Fig, 3 one of the wires 25 has shown mounted thereon a row of metallic shutters 3.3 which are stron adjacent one anoth r so that their edges just clear one another as closely as possible. The

lattice scree 13 of Fig. l is so placed behind the shut eras to obscure li ht which would ordinarily be admitted between the joints, Wire 25 is shown loop at the p int .30 where it is join to the short section 31I r ten oning to the sup p rt 2 whilethe vertical e tion of t w 29 is connected to the wire 23 which in turn is connected to the armature. of th r lay .34.

Gros sectional views of the wire 25. and the shutt rs 33 are shown in s. 4 and 5- In th s view i i evident hat the wires 25 .do ,not have a circular ross se ti n bu a pol onal nd s r roun d b s i ht y larger polygonal eve sec= rion to wh ch the gates 33 are atteqhed.

construction is especially advantageous inasmuch as it allows the shutter 33 to remain in a fixed position when once adjusted until it is again ad- 'justed either to its neutral position or a new position. In Fig. 6 another construction of shutter 33 is shown mounted upon the wire 25 in which the polygonal sleeve is replaced by a wire coiled about the wire 25 to form a support for the gate 33. This who may be held in its adglusted position by friction.

Before continuing the description of the other -modifications of this system, the operation of the above .l-flescribed embodiment will be given. The oscillator 11 produces, as stated above, an out- ;putwave-which is peaked and intermittent to the extent that it produces in the wire 28 a transverse wave with a definite loop which will travel along the Wire :28 .a tra definite speed, the proper speed being that of the speed in the transverse wires *25 divided by the number of wires. In other wor s. .thfi Wave in Wire .28. willtravel the distance between wires ,25 in the same length of time that it takes ,a transverse wave initiated in lwires ,25'to travel the length of one of these Wires. The wayesin the wires .25 will'be initiated in chr nological order with the resultlthat .jeiach gate will )be released iron; the wire ,25 in a serial rd r as the wa epas es therealong, each-shutter floating .for an instant. The oscillator 'll jjisso coordinated with the incoming signals that the proper shutter is loosened-at-the time the desired. impulse is impressed-on the field'so that the shut; ter will be magneticallymoved either forward or backward to admit light from the source l3 For instance, where a certain unitarea ,ota picture is represented by theflmaximum light in? tensity, a strong impulse will'strenglili'en the field oaclihst the shutter to its maximum opening when loosened by, the transverse wave from: the DISK/Elam: l1. This impulse will increase the field 5 at the proper time, whichis the time the pars titu ar shutter is loosened upon its wire; .When the transvers were. ha passed h shut er will ettle th position towhiohiit. a iostedby the 11 1; 311321 18maiil1thoi1e until the wire is ace; rated lay another transverse waveflinthe wire, thus pemuttmsthe eye t se i ht inithat as ticular unit area .duringthet me. the othershijts tors are s me a justed-l Iron thev second ash t h rt ohlo unit area hasjchan'ged light inten ity to zero at the transmitter'then he Shlllitfil will .return to its normal position by he action of ravity; ,It is to be understoo ha eoohstant fie d supplementing-th action of ay; ity may be employed. However, should the nit 130 area have a lesser degree ofJintensity hann e prior adjustment, then a newadjustment will be made by the lesser fieldstreng tho -,As, awave passes ,dQWllilhe vertical wire 28 each wirewill be activated in turn and oommutationisnm tallied mthout the use of rotating or oscillating me iums of large proportions. ,The' waveswhen theyreach the sectionZl will be absorbed, cling netingstandins waves in the wire. It s to he n ted that he fiel re gth is o p portioned that the shutters cannot; be moved thereby except when they have 'beenloosenecl by the elastic waves in he supp r n wir s: ,The strength of an auxiliary-field, when used to aid gravity, is also insuflicient to move the shutters when at rest. This is especially desirable. inasmuch as it permitsthe retention of any particu lar scene being transmitted by SiIIlDIY'JdECDll-i necting the oscillator 11 from the screens "The last imag rema n on messiah-indefinitely 3;;5

' When using this system as a'transmitter the receiver? will be 'replaced by an oscillator which opens and closes each-shutter as each shutter isloosen'edby the elastic waves in the wires sup-' porting-them. i i 1 1 Referring now to the modifications in Figs. '7 and 8, a cross wire-arrangement having vertical wires afl and horizontal wires 41which'may be mounted 'siinilar to"those'in" Fig. 2 is shown attached to'driving mediums 43 and i4: respectively. These sets of wires'liein two planes adjacent one another but'no't contacting. Abutting the-driving wire 43 is a motor crystal element 45, while transversely placed with'respect to driving wire 44, is a motor crystal l6. The crystal 451is connected to an oscillator 48 which also supplies an harmonic generator 49 the output'of the latter being impressedupon the crystal 46. By this arrangement, no waves introduced in one set' of wires are transmitted to the other directly through'the wires. The oscillator 48 furnishes to the crystal an electrical wave ofsuper-audible frequency while the harmonic generator 49 supplies thegen'erator'46 with a higher frequency. The wave produced in the driving wire' 44 is transverse while that in the driving wire 43 is lon g'itudinjal'but t ese waves beat together to produce'the necessary beat frequency desired, which may bje'with-in the audible; range.

Referring-now'to'l ig. 8 wire 40 and a wire 41 or Fig. Tis'shownhaving mounted thereon shuttei s 5l'and' 52 respectively, the shutters being in 'terconnected by means of a coil spring 53. This is a unit area section and is mounted at each intersectionof the wires 40 and; 41. The spring 53 ad the gates 51 and 52 provide a connection between theirequencie's in the wires and is so constructed that the assembly is" resonant to the beat frequency. When the two high frequencies arrive at the hinges of shutters simultaneously the beat frequency vibrates the assembly and loosens the shutters in the manner of that in Fi There isproducedftherefore,by this construction acommutating arrangement on the heterodyne principle in which a longitudinal wave is sent along a driving wave initiating either longitudinal or transverse waves inthe'wires in one plane, while another frequency is sentalong the wires in' jthei other plane, neither frequency of which has any effect upon loosening the shutters except when both frequencies are present "simultaneously. to form the beat vibration. A model his type of shutter provided an-opening'that increased along two sides in a perfect square. It is to be understood, that.the gates or some parts thereofare of magnetic'materialsoas to beafiectedv by the held as in Fig. 2. It is also to be understood that a single gate structure may be operated on the heterodyne principle by the use of parallel wires cooperating with wires 25 in Fig. 2 or cross wires asin Fig.1! with interconnecting Referring now to Figs. 9 and 10 two means of obtaining travelling waves without employing absorbing means is illustrated. In Fig. 9 a vertical driving wire is connected to horizontal screen wires 6i atpoints 62. I'he wire 60 is driven from a crystal 63 to initiate therein a transverse wave, this wave passing the last wire and continuing on toa fixed support 64 from which it is reflected. However, the length of the section of wire 60: beyond its utility'point, 'and the fre-- quency of the'periodic impulses placed'thereon, are so proportioned that immediately beyond the utility point, the reflected wave and the succeedingwave rneet and neutralize each other.

Similarly in Fig. 10 a coil spring '70 is fixedly mounted'at point 71 and attached to an electromagnetic driving element 72. Attached to the spring '70 at uniform distances are horizontal wires '73 for mounting shutters, and tensioning wires 74. Upon activation of the relay '72 from anoscillator '75 a longitudinal wave of condensations and rarefactions is produced in the coil ZO-Which is projected therealong to the point 'll-producing, as it goes along, a transverse wave in the wires 73. However, the section of the spring beyond its utility point and the frequency of the impulses impressed thereon are so proportioned that the reflected wave is neutralized by the -wave immediately following. These two figures, disclose, therefore, a construction for eliminating transverse and longitudinal reflections without the use of an absorbing medium. It is to be understood of course, that the wires 25 and 28 of Fig. 2 and the wires 48 and 41' of '7 may be equipped with an extension for neutralizing the reflected waves or may have the absorbing support such as section 21 in Fig.2.

In the above description of the invention, advantage has been taken of the speed of propagation of elastic waves in highly elastic mediinns such as steel and that this speed is controllable by tensioning and by the nature of the material. Furthermore, it will now be obvious that light intensification has been obtained by the use. of shutters in the above manner while a commutating system has been evolved without the use of rotating of heavy movable parts. Although it is realized that many modifications of the apparatus will occur to those skilled in the art based on the principles disclosed above, these equivalent systems are intended to be with-' in the scope of the appended claims.

What is claimed is:

1. In a system for the transmission of electrical impulses characterized by the light and shade densities or an object, a pluralityof elements mounted in a rectangular pattern, means forela'stic'ally sup-porting said elements, means for initiating elastic waves in said last mentioned means for loosening said elements on said supports in a serial order, and means for changing the position of said elements in accordance with the strength or" said iinpuls s.

2. In a television receiving system, a plurality of similar elements mounted upon elastic sup ports to form a rectangular pattern, means for initiating in said elastic supports elastic waves in chronological order, a field winding and means for adjusting each of said elements to positions depending upon'the strength of the currents in saidlfield winding, said elements remaining in their adjusted positions during intervals of time when no waves are present in said elastic supports.

3. In a television transmission system for transforming electrical currents characterized by the light and shade densities of an object into proportional light intensities, the combination of a frame, a plurality of Wires mounted on said frame, a plurality of movable shutters mounted adjacent one another on said Wires, an elastic medium perpendicular to said wires and connected thereto, and means for initiating. at one terminal of said medium an elastic wave perpend-icular to said wires for loosening said shutters upon said wires in a serial order.

4. In a television receiving system, a quadrilateral frame, a plurality of wires uniformly placed between two opposite sections of said frame, a plurality of shutters mounted on and adapted to rotate about said wires, an elastic medium perpendicular to said wires and attached thereto, means for initiating in said elastic medium elastic waves for actuating said wires in a chronological order, a winding surrounding said frame for creating an electric field in which said shutters are positioned, a light source at one side of said shutters for projecting light therethrough, and means adjacent said shutters for preventing light from passing therethrough when said shutters are in their normal positions.

5. In a television transmission system, a source of light, a framework between said light and an object to be scanned, light gates mounted elastically in said screen for admittin light in a chronological order, an oscillator, means for initiating elastic waves for actuating said elements Y with impulses from said oscillator, and means for opening and closing said gates.

6. In a picture receiving system or" the television type, a projection screen, a source of light, a framework intermediate screen and said source of light, a plurality of polygonal shaped wires connected to said framework, an elastic medium connected to said wires, an electrical unit for initiating in said wires vibrations at periodic intervals, said vibrations being initiated in said- Wires in a serial order, a plurality of shutters having sleeve portions surroundingsaid polygonal wires, and a winding surrounding said frame the field of said windingadjusting the position of said shutters upon said wires when said vibrations have loosened said shutters, said sleeve portions having a polygonal interior to coincide with said wires to maintain said shutters in the positions to which they are adjusted by said field.

'7. In a television receiving system,,a plurality of wires mounted in a plane at uniform intervals, a second plurality of wires mounted in another plane parallel to said first plane of wires, an elastic medium connected to said first plurality of wires, an elastic medium connected to said second plurality of wires, electrical units for initiating in said vibrations at different frequencies, a plurali v of shutters mounted on said first plurality of wires, a second plurality of shutters mounted on second plurality of wires, said shutters being physically interconnected, and electromagnetic meansfor adjusting the position of said shutters on said wires when said vibrations are present simultaneously at each assembly of shutters and connecting elements.

8. The method of recording television images which comprises generating elastic waves, applying said waves to movable shutters in chronological order, applying a plurality of signalling impulses to said shutters, moving said shutters in accordance with the combined elastic and signalling impulse and locking the shutters in position so that the image can be reproduced at any later time.

9. The method of obtaining a permanent television image which comprises generating elastic waves, applying said waves to movable shutters in chronological order, applying signalling impulses to said shutters, moving said shutters in accordance with the combined elastic and signalling impulse, locking said shutters in a permanent position and proiecting' a light hem thereth-rough'.

light and shade densities of an object, a phzralitu of parallel arranged wires inrthe same plane equally spaced from each other, a; plurality of shutters on said wires, an elastic medium penpendicular to said wires, means for initiating: in said elastic medium an impulse of periodic: fre quency in synchronism with said receivedinr pulses, means for projecting a constant intensity light beam on said shutters, and means: for fac tening one terminal of said elastic medium andof said wires beyond their utility point for obtaining neutralization of said" wave by the reflected from said fastening. point.

11. In a system for the: transmission of electrical impulses characterized by the light and shade densitiesof-an object, means for receiving said impulses, a light source, a screen, a field winding connected to'the output of said receiver means positioned in said field. intermediate said light source and saidscreen, saidmeans'com' ing a plurality of individual light gates, and elastic m means: for actuating said gates in acyclic order and in synchronism with the impression of said impulses upon said field.

1-2. In a television'system, meansfor generating electrical currents proportional to the light and shade intensities of unit areas of an object 01: image thereof means for transmitting saidv currents to areceiving point, elastic means atv said receiving point for translating said currents into spatially disposed light uni-t areas in accordance mg,

with said object, said means including means for generating elastic waves, a plurality of movable" elements mounted. onelastic supports and means for applying the elastic waves to said. movable elements in a chronological order, and means for retaining said light variations so disposed illlififlr nitely. g

13. In a television system, means for scanning an object or image thereof to produce electrical. currents proportional to the light and shade densities of unit areas thereof, means for transmlh ting said currents to a receiving point, a television receiving apparatus at said receiving point including a light gate having elementsrepresent-- ingunit areas of said. object scanned, and elastic means for serially controlling the openings of the elements of said light gate for any period of time and for maintaining their relative positions indefinitely at anyinstant of reception ofv said currents, said means including means for generating elastic waves, a plurality of movable elements mounted on elastic supports and means for applying the elastic waves tosaid movable elements'in a chronological order.

14, In a television system, means for receiving order, and elastic means for retaining the relative light and shade densities of each unit area for any length of time and at any instant.

15. In a television receiver, means for receiving current impulses characterizedby the light and shade densities of the unit areas of ascanned I50 future reproduction of said picture, said means including means for generating elastic waves, a plurality of movable elements mounted on elastic supports and means for applying the elastic Waves.

to said movable elements in a chronological order.

ALEXANDER MCLEAN NICOLSON. 

